Light emitting diodes (LEDs) are a type of semi-conductor device that emits visible light when biased in the forward direction. LEDs are typically smaller than standard bulb or filament type lamps, making LEDs desirable in applications where space is limited. A single LED typically produces less illumination than that of a standard light bulb. Therefore, in some applications, a plurality of LEDs may be combined in an array or other fashion to provide the same degree of illumination provided by one or more standard conventional lamps.
LEDs typically produce consistent and clear light that is more pleasant than conventional lamps. Also, unlike standard bulb lamps, LEDs do not have a high fail rate because they do not require a filament to produce light. Instead, light emitted by a LED is created by the generation of photons from materials within the LED. Accordingly, striations—which are present in convention filament-produced light sources—are not present with LEDs.
Conventional lamps are used for a variety of purposes, such as lighting industrial, commercial, and governmental applications. A light may be used by a government agency or commercial business, for example, to illuminate a sign along a roadway. Assemblies used for this purpose are typically called sign lighters. Conventional sign lighters typically comprise a housing containing a single lamp, such as a metal halide lamp. The conventional sign lighter is typically held perpendicular to the sign so as to direct light upwards to illuminate the sign. In this way, the sign may be read at night or during dark portions of the day.
Conventional sign lighters, however, typically consume vast amounts of energy and have a short life span. Maintenance costs, including the costs for replacing such conventional lamps can also be excessive. This is especially true for government or commercial entities who must ensure that sign lighters are active at all times.
In addition to the aforementioned problems, conventional sign lighters have additional problems such as excessive light spill (i.e., the light emitted from the sign lighter illuminates areas beyond the dimensions of the sign that are not intended to be illuminated) and striations. Additionally, the short life of bulbs and the effect of the light provided from conventional bulbs tend to wane over time. The color produced by conventional sign lighters, for example, has an undesirable yellow tint that becomes increasingly more pronounced and less desirable to users over time.
In comparison, LEDs are generally more energy efficient, more reliable, and last longer than conventional types of lighting, such as metal halide lamps. Despite this, LEDs have heretofore not been incorporated into applications to provide light for illuminating signs or for other commercial or governmental applications, such as street lamps. Further, LEDs have not been incorporated into a housing or system which can be retrofitted to replace existing metal halide and other conventional sign lighters.